Optimal preparation of Bose and Fermi atomic gas mixtures of ^(87)Rb and ^(40)K in a crossed optical dipole trap

We report on the optimal production of the Bose and Fermi mixtures with ^(87) Rb and ^(40)K in a crossed optical dipole trap(ODT).We measure the atomic number and lifetime of the mixtures in combination of the spin state |F=9/2,m_(F)=9/2> of^(40)K and |1,1>of ^(87) Rb in the ODT,which is larger and longer compared with the combination of the spin state |9/2,9/2> of^(40)K and 12,2) of ^(87)Rb in the ODT.We observe the atomic numbers of ^(87)Rb and ^(40)K shown in each stage of the sympathetic cooling process while gradually reducing the depth of the optical trap.By optimizing the relative loading time of atomic mixtures in the MOT,we obtain the large atomic number of ^(40)K(~6 ×10^(6)) or the mixtures of atoms with an equal number(~1.6 × 10^(6)) at the end of evaporative cooling in the ODT.We experimentally investigate the evaporative cooling in an enlarged volume of the ODT via adding a third laser beam to the crossed ODT and found that more atoms(8 × 10^(6)) and higher degeneracy(T/T_(F)=0.25) of Fermi gases are obtained.The ultracold atomic gas mixtures pave the way to explore phenomena such as few-body collisions and the Bose-Fermi Hubbard model,as well as for creating ground-state molecules of ^(87)Rb^(40)K.

Kármán vortex street in a spin–orbit-coupled Bose–Einstein condensate with PT symmetry

The dynamics of spin–orbit-coupled Bose–Einstein condensate with parity-time symmetry through a moving obstacle potential is simulated numerically. In the miscible two-component condensate, the formation of the Kármán vortex street is observed in one component, while ‘the half-quantum vortex street' is observed in the other component. Other patterns of vortex shedding, such as oblique vortex dipoles, V-shaped vortex pairs, irregular turbulence, and combined modes of various wakes, can also be found. The ratio of inter-vortex spacing in one row to the distance between vortex rows is approximately0.18, which is less than the stability condition 0.28 of classical fluid. The drag force acting on the obstacle potential is simulated. The parametric regions of Kármán vortex street and other vortex patterns are calculated. The range of Kármán vortex street is surrounded by the region of combined modes. In addition, spin–orbit coupling disrupts the symmetry of the system and the gain-loss affects the local particle distribution of the system, which leads to the local symmetry breaking of the system, and finally influences the stability of the Kármán vortex street. Finally, we propose an experimental protocol to realize the Kármán vortex street in a system.

Bose-Einstein凝聚态基态解的加权数值方法及稳定性分析

构造加权法离散归一化梯度流,求解玻色-爱因斯坦凝聚态(Bose-Einstein condensate, BEC)的基态解,整合和扩充了离散归一化梯度流的经典有限差分法。同时,结合冯·诺伊曼(von Neumann)条件和冻结系数法证明了不同加权因子下数值格式的稳定性条件。从局部截断误差大小来看,加权法的最优加权因子为1/2。数值实验验证了加权法的稳定性条件,表明加权法可有效求解基态,且在求解过程中能量随时间演化呈递减趋势。另外,当加权因子取值为1/3时,数值结果展示对应数值格式在空间方向具有二阶收敛性。

Eigenstate Distribution Fluctuation of a Quenched Disordered Bose–Hubbard System in Thermal-to-Localized Transitions

We study the thermalization of a quenched disordered Bose–Hubbard system. By considering the eigenstate distribution fluctuation, we show that the thermal to many-body localized transition is always connected to a minimum of this distribution fluctuation. We also observe a Mott-localized regime, where the system fails to thermalize due to the strong on-site repulsion. Lastly, we show how to detect this eigenstate distribution fluctuation in a cold atom system, which is equivalent to measure the Loschmidt echo of the system. Our work suggests a way to measure the thermal-to-localized transitions in experiments, especially for a large system.

Topological aspects in a two-component Bose condensed system in a neutron star

By making use of Duan-Ge＇s decomposition theory of gauge potential and the topological current theory proposed by Prof. Duan Yi-Shi, we study a two-component superfluid Bose condensed system, which is supposed to be realized in the interior of neutron stars in the form of the coexistence of a neutron superfluid and a protonic superconductor. We propose that this system possesses vortex lines. The topological charges of the vortex lines are characterized by the Hopf indices and the Brower degrees of C-mapping.

Amplitude Squeezing of a Weakly Interacting Bose System with Spontaneous U(1) Symmetry Breaking

We study the quantum fluctuations and the amplitude squeezing of a weakly interacting Bose system withspontaneous U(1) symmetry breaking.It is found that this system can exhibit amplitude squeezing.

Legendre配置谱方法求解Bose-Einstein凝聚态的基态解

近年来,有关Bose-Einstein凝聚态基态解的实验研究已经取得了一系列重要的成果.该文在相关研究成果的基础上,首先通过降维和无量纲化方法将Bose-Einstein凝聚态基态解问题转换成能量泛函极值问题,在离散该泛函时,尝试使用Legendre配置谱方法离散该能量泛函的一维和二维情形.其次,对该能量泛函极小值问题进行了数值模拟.最后,通过分析实验数据结果和图像得出,针对非旋转的Bose-Einstein凝聚态的基态解问题可以使用Legendre配置谱方法来求解,且数值结果的误差较小.

Mode dynamics of Bose–Einstein condensates in a single-well potential

We investigate dynamics of Bose–Einstein condensates(BECs) in a single-well potential using the mode-coupling method. Symmetry is shown to play a key role in the coupling between modes. A proper mode-coupling theory of the dynamics of BECs in a single-well potential should include at least four modes. In this context, the ideal BEC system can be decomposed into two independent subsystems when the coupling is caused by external potential perturbation and is linear. The mode dynamics of non-ideal BECs with interaction shows rich behavior. The combination of nonlinear coupling and initial condition leads to the different regimes of mode dynamics, from regularity to non-regularity, which also indicates a change of the dependence of coupling on the symmetry of modes.

Bose公司首套media system车载影音娱乐系统

在2007日内瓦车展上．Bose公司推出了首套车载影音娱乐系统Bosemediasystem．该系统融合娱乐、导航、通讯和信息于一体．减少了驾驶时通讯和娱乐的复杂操作。新款Ferrari 612 Scaglietti上搭载的全新Bosemediasystem包含有一整套的环绕声系统。

Entanglement and thermalization in the extended Bose–Hubbard model after a quantum quench: A correlation analysis

Exploring the role of entanglement in quantum nonequilibrium dynamics is important to understand the mechanism of thermalization in an isolated system. We study the relaxation dynamics in a one-dimensional extended Bose–Hubbard model after a global interaction quench by considering several observables: the local Boson numbers, the nonlocal entanglement entropy, and the momentum distribution functions. We calculate the thermalization fidelity for different quench parameters and different sizes of subsystems, and the results show that the degree of thermalization is affected by the distance from the integrable point and the size of the subsystem. We employ the Pearson coefficient as the measurement of the correlation between the entanglement entropy and thermalization fidelity, and a strong correlation is demonstrated for the quenched system.

快乐旅途 Bose media system 正式发布

Bose公司近日推出了首套车载影音娱乐系统，独家科技加上超前的使用界面使其融合娱乐．导航．通讯和信息于一体。2007上海国际车展展出的Ferrari 612 Scaglietti上搭载的全新Bose media system就是Bose公司为这辆法拉利座舱量“声”定制的。

家庭音乐系统 BOSE 妙韵音乐系统Wave Music System

对于很多音乐爱好者来说，Hi-Fi音响组合繁琐的搭配和相对高昂的售价是他们难以接受的，而台式迷你组合音响仍然有着音质不够理想和使用不够简便的缺点。在这样的背景下，美国著名的音响器材制造商BOSE推出了完全集成在一个单体内的多功能高品质妙韵音乐系统Wave Music System，它酷似一台复古收音机的外壳内集成了BOSE独创的双锥形音频导波管扬声器技术，可以从小巧的箱体里发出更低沉而纯净的低音。同时集成了吸八式CD播放机和FM／AM收音机，可以外接iPod、MP3播放器、电脑、电视机或者DVD播放机等音源，享受各类音乐播放设备的完美音乐表现．还具备双响闹铃功能。

BOSE Wave Music System一体机

集CD、AM／FM收音调谐等功能于一体的Wave Music System是1999年发售的WaveRadio／CD之后续机型。它保留了BOSE原有的60mm全频带立体声喇叭和闹钟，但将面板上的所有操控按键省略并改由遥控操作。新版本还支持了MP3音乐的播放。外形尺寸为W368×H106×D219mm，重仅3．9kg。

Quantum degenerate Bose–Fermi atomic gas mixture of 23Na and 40K

We report a compact experimental setup for producing a quantum degenerate mixture of Bose23Na and Fermi40K gases. The atoms are collected in dual dark magneto–optical traps(MOT) with species timesharing loading to reduce the light-induced loss, and then further cooled using the gray molasses technique on the D2line for23Na and D1line for40K. The microwave evaporation cooling is used to cool23Na in |F = 2, mF= 2〉 in an optically plugged magnetic trap, meanwhile,40K in |F = 9/2, mF= 9/2〉 is sympathetically cooled. Then the mixture is loaded into a large volume optical dipole trap where23Na atoms are immediately transferred to |1, 1〉 for further effective cooling to avoid the strong three-body loss between23Na atoms in |2, 2〉 and40K atoms in |9/2, 9/2〉. At the end of the evaporation in optical trap, a degenerate Fermi gas of40K with 1.9 × 10^(5) atoms at T/TF= 0.5 in the |9/2, 9/2〉 hyperfine state coexists with a Bose–Einstein condensate(BEC) of23Na with 8 × 10^(4) atoms in the |1, 1〉 hyperfine state at 300 n K. We also can produce the two species mixture with the tunable population imbalance by adjusting the 23Na magneto–optical trap loading time.

Probability of Obtaining the Planck Constant, in a Universe Modeled as a Giant Black Hole by Bose Einstein Condensates of Gravitons Using Hawking Argument and Scaling

We use the methodology of A. D. Linde to model the probability of obtaining a cosmological constant which is in turn affected by scaling arguments for a Bose Einstein gravitational condensate as given by Chavanis, in 2015. The net result, is that the scaling argument so provided allows for a gravitational constant commensurate with the size of the Universe, using arguments which appear to be simple but which give, if one has the conditions for modeling the Universe as a “black hole” virtually 100 % chance for the cosmological constant arising.

Spontaneous U(1) Symmetry Breaking in Coupled Bose System

Adding a U（1） symmetry breaking term √V（λ1a0 ＋ λ1＊a0） ＋ √V（λ2b0 ＋ λ2＊b0） to Bogoliubov＇s truncated Hamiltonian HB for a weakly interacting coupled Bose system, by using the mean-field approximation rather than the c-number approximation, we And that, via a Feshbach resonance at zero temperature, the states of the coupled Bose system are generalized SU（1,1） SU（1,1） coherent states. The Bose-Einstein condensation occurs in response to the spontaneous U（1） symmetry breaking.

Modified White Hole Enthalpy Coupled to Quantum Bose-Einstein Condensate at Extremely Low Entropy

We model the universe as a white hole, and in the process we perform detailed analysis of the enthalpy equation of the modified white hole, and we get a much detailed picture of when and how did;quantum gravity (cosmology) phase, inflationary phase, and the acceleration phase of the universe happened. We determine the field equations of the modified white hole and evolve the scale factor and compare the evolution to the thermodynamic properties of the universe. We also illustrate that the strong energy condition is violated, but both the null energy condition and the strong cosmic censorship are not violated. Lastly, we couple the enthalpy to the Bose-Einstein condensate at extremely low entropy at the quantum gravity (cosmology) regime. Thereafter, we determine the unstable condition of the Bose-Einstein quantum equation which we interpret as the moment when the big bang occurred.

Bose体系中外场对体系熵的影响

讨论了Ｂｏｓｅ体系中外场对体系熵的影响．通过对量子情况下二维带电Ｂｏｓｅ子体系在磁场中熵的计算，发现存在磁场时二维带电Ｂｏｓｅ子体系的熵有可能大于无磁场时相同体系的熵．从而证明了对于在外场中的量子Ｂｏｓｅ体系，Ｂａｉｅｒｌｅｉｎ的观点不成立．

基于Bose-Einstein凝聚腔光力学系统的可调控相干完美吸收（英文）

研究了基于Bose-Einstein凝聚(BEC)腔光力学系统中的相干完美吸收现象,阐述了诱导相干完美吸收产生的条件,分析了强耦合BEC光力学腔发生相干完美吸收时的能量转换。通过控制泵浦场功率可以有效调制相干完美吸收。当相干完美吸收产生时,输入探测场能量完全转化为机械振子和腔场能量而不产生任何透射和反射,并且通过改变腔的品质因子可实现能量萃取。强耦合BEC腔光力学系统为基于相干完美吸收的换能器、调制器及光开关等潜在应用提供了理论基础。

玻色-爱因斯坦凝聚与光场作用的保真度

利用量子信息论和数值计算方法,对Pólya场态与玻色-爱因斯坦凝聚原子相互作用系统的量子态保真度演化问题进行了研究。讨论了玻色-爱因斯坦凝聚原子间的相互作用强度、 Pólya场态概率参数和分布参数,以及这些物理参数如何影响量子态保真度随时间的演化。研究结果表明:上述三种物理参量均可调制信号传输中的量子态保真度,其中光场概率参数η对量子态保真度的变化影响最大,当η=0.01时,量子信息保真度的值非常接近信息理想传输的情形;另一方面,凝聚原子间的耦合强度越大,量子态保真度呈现出的周期性振荡也越强,但量子态保真度的取值范围不变。